Question about 1989 GMC K1500
Transmision wont shift into second gear and over drive
You need to retrieve transmissions faulty code with a scanner.
It looks like The PCM (powertrain control module) is in limping mode. It is the default mode when there is a faulty Transmission or engine code.
Hope it helps.
Posted on Feb 18, 2019
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Posted on Jan 02, 2017
You might want to try this if its got a kick down cable unhook it from throutle body and pull it out as far as you can and let it snap back, do this a few of times, sometimes a valve gets hung up inside valve body of trans. and won't let it shift. If that don't help you may have to pull pan to dislodge it if thats the problem. chk. the plug on trans. (Its a 4 wire white plug) with test light with key on to see if there is power down there one will be hot, thats for overdrive, now on top of intake in front throutle body there is a sending unit that looks like a temp. sending unit with a 2 wire plug on it that sends a signial down to that plug when engine gets to temp. to let it shift to overdrive. Maybe this will help, or give you some ideas.
Posted on Mar 02, 2009
Maybe, but won't know till you take it too tranny shop. Even iif it is done a rebuilt is still cheaper than brand new. And, less you drive it now less damage done.
Posted on Dec 29, 2008
-----check possible tps [throttle position sensor ]circuit for damage or faulty sensor----if good check the fuses and trans harness for shorts damage or disconnection,check o2 sensors wiring possible ground to exhaust ,or internal leak 2nd gear apply circuit[servo assembly or 1-2 accumulator] or poor pump pressure
Posted on Feb 13, 2010
rec check fluid first. If trans fluid hasn't been changed in last 30,000 miles change fluid, filter and pan gasket. At that time inspect for foreign materials in bottom of pan or on magnet if you have one. If truck has over 100K and fluid was never changed you may have more problems if changing the fluid.
Posted on Jun 17, 2010
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